What is a larvicide?

A larvicide is defined as an insecticide that specifically targets the larval stage of insects. Larvicides are designed to disrupt the development and growth of larvae, preventing them from maturing into adult insects. This is critical in pest management strategies, particularly for insects that can carry diseases or become nuisances in their adult forms. By focusing on larvae, larvicides can efficiently reduce the population of pests before they reach maturity and begin reproducing, thus breaking the lifecycle of these insects.

The other options present concepts that are not applicable to the definition of a larvicide. An insecticide targeting adult insects refers to a different category of pest control, while a substance that prevents egg laying might relate more to ovicides, which are designed to kill eggs rather than larvae. A chemical that repels all insects does not accurately describe the function of a larvicide, as larvicides do not repel insects but actively kill or inhibit larvae. Thus, the identification of option B as the correct answer aligns with the specific function and purpose of a larvicide in pest management practices.